The present invention concerns a linkage for coupling vehicles to ground-engaging implements, for example for coupling a wheeled vehicle to a snow-plough or to agricultural machinery.
Such couplings are well-known, an example being the so called "three-point linkage" which has three pivotting linkages which can pivot up and down to allow the coupled implement to ride over bumps etc. in the ground and a fourth linkage for lifting the implement clear of the ground for transportation.
Although such linkages do allow the implement to pivot upwardly to accommodate uneven ground, they cannot allow the implement to tilt so that one side of the implement is lower than the other. Such tilting action is desirable to keep the implement close to the ground when the ground is higher on one side of the implement than on the other. A further disadvantage of these linkages is that, especially when being carried above the ground, they allow the implement to sway from side to side, which is undesirable and can be dangerous.